Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Mary Anne O'Callaghan, M.D.

Family Medicine Physician in El Segundo, CA · enumerated 2011.

Data current as of Jul 13, 2026 · sourced from CMS NPPES

National Provider Identifier

1932489408

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Registry record

Entity type Individual (Type 1)

Name Mary Anne O'Callaghan

Credential M.D.

Sex Female

Practice address 845 Maryland St, El Segundo, CA, 90245

Phone (310) 640-9604

Enumeration date Aug 27, 2011

Last updated in NPPES Aug 27, 2011

Taxonomy & licenses

207Q00000X Family Medicine Physician Allopathic & Osteopathic Physicians · License AFE19605 (CA) Primary

MD · Doctor of Medicine: A physician who completed medical school (allopathic medicine), residency training, and state licensure. About the MD credential

What is an NPI number?

A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes, even if the provider moves or changes specialty.

Read the full guide → Validate an NPI →

Frequently asked questions

What is the NPI number for Mary O'Callaghan?

The National Provider Identifier (NPI) for Mary O'Callaghan is 1932489408, a Type 1 (individual) record in the CMS NPPES registry.

Where does Mary O'Callaghan practice?

The practice location on file with NPPES is in El Segundo, CA. Providers can have multiple locations; NPPES lists the primary practice address.

Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2011-08-27.